Adjustable and convertible putter

ABSTRACT

An adjustable and convertible putter is provided for use with any of the conventional putting styles or with an underarm putting style. The putter has a head connected to the shaft with an adjustable connector that permits the lie angle and the loft angle to both be adjusted within a wide range of angular orientations. A shaft connector assembly may be provided on the shaft with a first portion of the connector assembly being assembled to the lower portion of the shaft and a second portion of the connector assembly being attached to an upper portion of the shaft. The upper portion of the shaft may be provided in a length appropriate for an underarm putter, a belly putter, or a long putter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application Ser.No. 61/257,521 filed Mar. 15, 2013 the disclosure of which is herebyincorporated in its entirety by reference herein.

TECHNICAL FIELD

This disclosure relates to a putter used in the sport of golf.

BACKGROUND

One of the most important aspects of the game of golf is putting. A widevariety of putters have been developed over the years in an effort toprovide every golfer with the putter that has the desired feel and,hopefully, produces the desired result as more one putts.

Conventional putters include a putter head attached to the lower end ofa shaft and a grip that is provided on the upper end of the shaft.Putter heads may be one of many types of blades or one of many widelyvaried types of mallets. Putters generally are provided with a shaftthat is of a fixed length with a grip provided at the upper end of theshaft or provided at the upper end with an auxiliary or intermediategrip provided below the grip at the upper end.

There are four accepted putting styles that are currently in use thatare normally used with one of three different length putters. A standardlength putter used in the standard putting style has a shaft that isapproximately 800 mm to 900 mm and may be shorter for women or childrenor longer for taller men. A belly putter is used in the belly puttingstyle and generally has a shaft of 950 mm to 1100 mm in length and isdesigned to be anchored against the stomach of a golfer. A long putteris used in the long putting style and has a shaft that is longer than1100 mm and is designed to be anchored at the chest or chin of a golfer.A golfer using “side-saddle” putting style also may utilize the longputter.

Putters are generally purchased in standard combinations of the headshaft and grip and are not adjustable or convertible in any way. If agolfer, after purchasing a standard length putter, wishes to try a bellyputter or a long putter, he must purchase a completely different putter.

The loft (vertical face angle) and lie angle (toe up/toe down) of theputter head are normally fixed and cannot be adjusted or calibrated.Golfers may change their putting stance so that the golf ball is struckby the putter head either forward in the stance, in the middle of thestance, or in the back of the stance. The putter face becomes morepositively lofted toward the front of the putting stance and morenegatively lofted toward the rear of the putting stance. The loft isdetermined based upon where the golf ball is to be struck by the putteror putter head. Conventional putters do not have a loft angle adjustmentmechanism.

Golfers may wish to stand closer to or further from the golf ball. Asthe point of contact of the putter head with the golf ball moves furtherfrom the golfer's feet, the lie angle of the shaft relative to theground increases.

If it is desired to strike the ball with a putter head at a locationcloser to the golfer's feet, the lie angle is reduced and the shaftextends upwardly at a more vertical angle. With a conventional putter,it is not possible to change the loft angle or lie angle of the putterhead relative to the shaft.

The putter head is normally attached to the shaft with the blade of theputter square to the direction that the ball is to be stroked. Somegolfers may want to stroke the golf ball with an open-face or aclosed-face or compensate for a defect in their putting stroke. However,conventional putters do not permit adjustment of the putter headrelative to the shaft and grip to provide an open or closed face.

This disclosure is directed to solving one or more of the above problemsand other problems associated with conventional putter designs assummarized below.

SUMMARY

According to one aspect of this disclosure, an under the arm putter isdisclosed that allows a golfer to use a long putter using a puttingstance for a traditional or standard sized putter. Lodging a long putterunder the armpit allows a golfer to put with a normal stance whileobtaining the benefits of a long putter or belly putter preventing themfrom breaking their wrists while putting.

According to one aspect of the present invention, an adjustable andconvertible putter is provided that may be adapted for use with any ofthe conventional putting styles or with an underarm putting style. Theputter has a head connected to the shaft with an adjustable connectorthat permits the lie angle and the loft angle to both be adjusted withina wide range of angular orientations. The lie angle of the putter may beadjusted to move the toe up or down. The angular orientation of the faceof the putter may be adjusted to change the loft of the putter facewhich allows the putter to lie on the ground in a functional manner withthe appropriate loft whether the putter is positioned in the front of aplayer's stance, the middle of the stance, or in the back of a putter'sstance. The adjustable connector also allows the putter face to beadjusted to a square, open or closed orientation.

According to another aspect of the invention, a connector assembly maybe provided at an intermediate location on the shaft. A first portion ofthe connector assembly may be assembled to the lower portion of theshaft with a second portion of the connector assembly being attached toan upper portion of the shaft. The upper portion of the shaft may beprovided in a length appropriate for an underarm putter, a belly putter,or a long putter.

According to another aspect of the invention, the shaft may beinterchanged and used with different types of putter heads. For example,if a golfer wishes to convert from a two ball putter to a mallet putter,but continues to use the same shaft and putting style (belly, standard,long putter, etc.), the shaft may be easily disconnected from one putterhead and reconnected to a different putter head.

According to yet another aspect of the present invention, the adjustableand convertible putter disclosed may be used as a standard putter, abelly putter, a traditional long putter, an under the arm long putter,or as a side saddle putter. With each different length and addressposition, the lie and loft angles may be different but with the presentinvention both angles may be adjusted with a single adjustment mechanismto the exact position desired by the golfer. Depending upon the positionof the ball relative to the golfer's feet at address being centered,forward, or rearward, it may be necessary to adjust the loft angle(vertical face angle) of the putter head relative to the shaft.Depending on the how far the golfer chooses to stand away from the ballat address, it may be necessary to adjust the lie angle (toe up/toedown) of the putter head relative to the shaft. The putter head may alsobe rotated relative to the shaft to turn the head from a square positionto an open or closed position. Further, according to the presentinvention, the shaft may be used and combined with different heads toallow a golfer to convert from a mallet putter to a two ball putter orfrom one mallet putter to another, or one type of putter to another asdesired.

According to a further aspect of this disclosure, a putter is disclosedthat comprises a shaft with a grip provided on at least an upper end ofthe shaft. A head is connected to the shaft by a connector that includesa first part attached to the shaft and a second part connected to thehead. The first part and the second part define a ball joint connectionbetween the shaft and the head that are configured to connect the headto the shaft in a range of angular orientations to permit a lie angleand a loft angle of the head to be adjusted and fixed in a selectedorientation relative to the shaft.

The first part of the connector may comprise a ball end including acylindrical stub shaft adapted to be attached to a lower end of theshaft and a spherical lower portion. The second part of the connectormay further comprise a receptacle that defines a partially sphericalsurface and a threaded locking member that may be loosened to change anangular orientation of the head relative to the shaft and tightened tofix the angular orientation of the head relative to the shaft.

The receptacle may further comprise an adapter having a plurality offingers on an upper end that have an outer surface that form a frustumof a cone with an increasing diameter in a vertical direction. The headdefines an opening that receives the adapter. A lower portion may definea threaded opening that receives the threaded locking member. Thethreaded locking member may be used to loosen the engagement of thefingers on the ball end by extending the adapter out of the opening. Thethreaded locking member may be used to tighten the engagement of thefingers by drawing the adapter into the opening.

Alternatively, the receptacle may further comprise a socket having apartially spherical surface on an upper end that is secured in anopening in the head. The socket may define a threaded hole that opensinto the partially spherical surface. A threaded fastener may bereceived in the threaded hole with the fastener being untightened toloosen the engagement of the fastener on the ball end. The threadedfastener may be tightened to fix the ball end in place in the socket.

The opening in the head may include a shoulder that is disposed abovethe spherical lower portion of the ball end when the ball end isdisposed in the opening in the head. The shoulder may have a lowersurface that is a concave ring that conforms to a part of the sphericallower portion of the ball end. The socket may have a threaded outersurface and the opening in the head may have a threaded inner surface sothat the socket is retained in the opening by the threaded outer surfaceengaging the threaded inner surface. A shoulder may be provided on alower end of the socket and a countersink bore may be defined in thelower surface of the head. The socket may be screwed into the opening inthe head to engage the shoulder in the countersink bore.

The shaft may further comprise a lower portion approximately 800-900 mmin length and an upper portion approximately 150-200 mm in length. Aconnector assembly may be provided that is adapted to secure the upperportion of the shaft to the lower portion of the shaft to adapt theshaft to be used as a belly putter. An intermediate grip may be providedon an upper end of the lower portion.

Alternatively, the shaft may further comprise a lower portion and anextended length upper portion. A connector assembly may be provided thatis adapted to secure the extended length upper portion of the shaft tothe lower portion of the shaft to function as a long putter

According to another aspect of this disclosure a putter is provided thatincludes a putter head and a shaft connected to the putter head. Theshaft has a lower portion that includes a first portion of a connectorassembly and an upper portion that includes a second portion of theshaft. A first grip may be provided on the lower portion of the shaftbelow and adjacent to the first portion of the connector assembly. Asecond grip may be provided on the upper portion of the shaft in aspaced relationship relative to the second portion of the connectorassembly and adjacent to an upper end of the upper portion of the shaft.

The upper portion of the shaft when used as a belly putter may have alength LB that is less than the length of the lower portion of theshaft. The upper portion of the shaft when used as a long putter mayhave a length LL that is greater than the length LB of the upper portionof the shaft of a belly putter.

The upper portion of the shaft may be selected from a first portion thathas a length LB that is less than the length of the lower portion of theshaft, and a second upper portion of the shaft that may have a lengthLL, wherein the first portion is interchangeable with the secondportion.

The shaft may be configured to connect the head to the shaft in a rangeof angular orientations to permit a lie angle and a loft angle of thehead to be adjusted and fixed in a selected orientation relative to theshaft. The shaft may be connected to the putter head by a ball jointthat further comprises a ball end including a cylindrical stub shaftadapted to be attached to a lower end of the shaft and a spherical lowerportion. The ball joint may further comprise a receptacle on the putterhead that defines a partially spherical surface and a threaded lockingmember that may be loosened to change an angular orientation of the headrelative to the shaft and tightened to fix the angular orientation ofthe head relative to the shaft.

The above aspects of this disclosure will be described in greater detailbelow with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevation view of a standard shaft with a threadedconnection assembly and an upper portion of the shaft sufficient toextend the shaft for use as an under-the-arm putter;

FIG. 2 is a fragmentary exploded perspective view of a three-partconnector used to connect a shaft to a putter head;

FIG. 3 is a fragmentary cross-sectional view of the three-part connectorassembly shown with the shaft connected to the putter head in a fixedangular orientation;

FIG. 4 is a fragmentary side elevation view of a shaft and putter headconnected together at a selected loft angle with other loft angleorientations of the shaft relative to the putter head being shown inphantom lines;

FIG. 5 is a fragmentary perspective view of a shaft and putter headillustrating two different lie angle adjustments;

FIG. 6 is a fragmentary perspective view of a putter head and shaftillustrating the ability to adjust the angle of the face to an openangular orientation or closed angular orientation and also illustrates athreaded connector assembly for connecting the lower portion of theshaft to an interchangeable upper portion of the shaft;

FIG. 7 is a front elevation view of a standard putter;

FIG. 8 is a front perspective view of a standard putter shaft with athreaded connector assembly and an upper portion of the shaft sufficientto extend the shaft for use as a belly putter;

FIG. 9 is a front elevation view of a standard putter shaft with athreaded connector assembly and an upper portion of the shaft sufficientto extend the shaft for use as a long putter;

FIG. 10 is an exploded fragmentary perspective view of a putter head andshaft showing an alternative adjustable connector assembly; and

FIG. 11 is a cross-sectional view of the putter head and shaft connectedby the adjustable connector assembly shown in FIG. 10.

DETAILED DESCRIPTION

A detailed description of the illustrated embodiments of the presentinvention is provided below. The disclosed embodiments are examples ofthe invention that may be embodied in various and alternative forms. Thefigures are not necessarily to scale. Some features may be exaggeratedor minimized to show details of particular components. The specificstructural and functional details disclosed in this application are notto be interpreted as limiting, but merely as a representative basis forteaching one skilled in the art how to practice the invention.

Referring to FIG. 1, an underarm putter 10 is shown to include a grip 12at an upper end 14 of a shaft 16. A putter head 18 is shown at the otherend of the shaft 16 with a golf ball 20 in position to be stroked withthe putter head 18. A golfer 24 is shown in phantom line with the grip12 of the underarm putter 10 disposed in the armpit 26 of the golfer 24.

Referring to FIGS. 2 and 3, a ball end 30 is provided on the shaft. Acylindrical stub shaft 32 extends from the ball end 30 and is receivedin the lower end of the shaft 16. An adapter is generally indicated byreference numeral 36 and defines a ball seat 38 that is a concave,partially spherical surface within the adapter 36. A plurality offingers 40 are provided on the upper end of the adapter 36. An outersurface 42 of the fingers, in combination, form a frustum of a cone withan increasing diameter in the vertical direction. A threaded opening 44is defined by a lower portion 46 of the adapter 36.

A receptacle 48 is defined within the putter head 18. The receptacle 48is partially defined by a tapered wall 50 that receives the outersurface 42 of the fingers 40 when the adapter 36 is assembled to theputter head 18. A cylindrical wall 52 partially defines the receptacle48 and receives the lower portion 46 of the adapter 36 when the adapter36 is assembled to the putter head 18. A countersink 56 is defined inthe putter head 18 and extends upwardly from the bottom of the putterhead 18. A screw 58, including a threaded shaft 60 and a head 62, isinserted through the countersink 56 and into the threaded opening 44defined by the adapter 36. The screw 58 is tightened to draw the adapter36 into the putter head 18 until the screw 58 is tightened against ashoulder 64 created by the countersink 56. As the screw 58 is tightened,the outer surface 42 of the fingers 40 are drawn downwardly into thereceptacle 48 so that the fingers are forced into engagement with theball end 30 by the tapered wall 50 thereby locking the shaft 16 to theputter head 18. To adjust the lie angle or loft angle of the putter head18 relative to the shaft 16, the screw 58 is simply loosened and theshaft is repositioned at the desired angular orientation, and the screw58 is then tightened. The putter head 18 may also be rotated relative tothe shaft when the screw 58 is loosened and then may be locked into aparticular open or closed orientation by tightening the screw 58.

Referring specifically to FIG. 3, the putter head 18 is shown securelyattached to the shaft 16. The ball end 30 is received within the ballseat 38 and is secured to the shaft 16 by cylindrical stub shaft 32. Thescrew 58 is shown fully tightened against the shoulder 64 and thethreaded shaft 60 of the screw 58 is fully tightened into the threadedopening 44 defined by the adapter 36. When the screw 58 is fullytightened, the fingers 42 are forced into engagement with the ball end30 as the outer surface 42 of the fingers 40 are drawn downwardlyagainst the tapered wall 50.

Referring to FIG. 4, the loft angle adjustment of the shaft 16 relativeto the putter head 18 is illustrated by the arrows adjacent the shaft16. The shaft 16 may be adjusted from the upright orientation shown insolid line. If the putter head 18 at address is moved back in thestance, the loft angle of the putter may be adjusted to provide a morepositive loft angle to compensate for the upper end 14 of shaft 16 beingin front of the putter head 18. If it is desired to position the ballmore forward in the golfer's stance, the loft angle of the putter may beadjusted to a more negative loft angle to compensate for the upper end14 of the shaft 16 being behind the putter head 18.

Referring to FIG. 5, a putter head 18 and shaft 16 are shown with theball end 30 received in the putter head 18. The fingers 40 are showndrawn down into the putter head 18. The shaft 16 is shown in phantomlines in two positions illustrating the ability to adjust the lie angle(toe up/toe down) of the putter head relative to the shaft 16.

Referring to FIG. 6, the putter head 18 is shown attached to a lowerportion 16LP of the shaft. The lower portion 16LP is connected by ballend 30 to the putter head 18. A threaded connector assembly 70 is shownas an exploded portion of the view. The connector assembly includes afirst portion generally indicated by reference numeral 72. The firstportion 72 includes a cylindrical stub shaft 74 that is received inlower portion 16LP of the shaft. A threaded stub shaft 76 is provided onthe opposite side of a lower body portion 78 from the cylindrical stubshaft 74. A second portion 80 of the threaded connector assembly 70includes a cylindrical stub shaft 82 on one side of an upper bodyportion 84. The upper body portion 84 defines a threaded bore 86 in theopposite end of the upper body portion 84 from the cylindrical stubshaft 82. The cylindrical stub shaft 82 is received in an upper portionof an underarm putter 16U to provide an underarm putter such as thatshown in FIG. 1. Of course, the orientation of the threaded connectorassembly 70 may be reversed with the threaded stub shaft 76 extendingfrom the bottom 84 with the threaded bore 86 being defined in the lowerbody portion 7;8.

FIG. 6 also illustrates the rotary adjustability of the putter head 18with two arcuate arrows near the lower end of the shaft 16.

Referring to FIG. 7, a standard putter is illustrated to include aputter head 18 in position for contacting a golf ball 20. The putterhead 18 is attached to a standard length shaft 16S for use with aconventional putting style. The threaded connector assembly 70 isprovided at the upper end 14 of the shaft 16S. A grip 12 is attached tothe upper end 14 of the shaft 16S.

Referring to FIG. 8, a belly putter is illustrated that includes aputter head 18 addressing a golf ball 20. The standard length shaft 16Sis connected to putter head 18 on its lower end. The threaded connectorassembly 70 connects the standard length shaft 16S to a belly putterportion 16B. The belly putter embodiment includes the belly putterportion 16B and includes the standard putter grip 13 and an upper grip12. Two grips are typical with a putter used in the belly puttingstance. The belly putter may also be used as a side saddle putterdepending upon the golfer's preference.

Referring to FIG. 9, a long putter is illustrated that includes a putterhead 18 addressing a golf ball 20. The standard length shaft 16S isconnected to putter head 18 on its lower end. The threaded connectorassembly 70 connects the standard length shaft 16S to a long putterportion 16L. The long putter embodiment includes the standard puttergrip 13 and an upper grip 12. One or two grips are typical with a putterused in the long putting stance. The long putter may also be used as aside saddle putter depending upon the golfer's preference.

Referring to FIG. 1, an under-the-arm putter is illustrated that issomewhat longer than a conventional long putter. The standard lengthshaft 16S is connected by the threaded connector assembly 70 to anunder-the-arm portion 16U. The under-the-arm putter embodiment mayinclude two more grips 12, 13.

Referring to FIGS. 10 and 11, an alternative adjustable putter isdisclosed that has an adapter 90 including a socket 92 that has apartially spherical surface 94 on an upper end that is secured in anopening 96 in the head 98. The socket 92 defines a threaded hole 100that opens into the partially spherical surface 94. A threaded fastener102 is received in the threaded hole 100. The fastener 102 isuntightened to loosen an engagement of the fastener 102 on the ball end30 and is tightened to fix the ball end 30 in place in the socket 92.

The opening 96 in the head 98 includes a shoulder 104 that is disposedabove a spherical portion 106 of the ball end 30 when the ball end isdisposed in the opening 96 in the head 98. The shoulder 104 has a lowersurface 108 that is configured as a concave ring that conforms to a partof the spherical lower portion 106 of the ball end 30. The socket 92 hasa threaded outer surface 110 and the head 98 has a threaded innersurface 112. When the socket is retained in the opening 96 by thethreaded outer surface 110 engaging the threaded inner surface 112, ashoulder 114 provided on a lower end 116 of the socket 92 is tightenedagainst a countersink bore 118 defined in a lower surface 120 of thehead 98. The socket 92 is screwed into the opening in the head 98 untilthe shoulder 114 of the socket 92 engages the countersink bore 118.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the disclosed apparatusand method. Rather, the words used in the specification are words ofdescription rather than limitation, and it is understood that variouschanges may be made without departing from the spirit and scope of thedisclosure as claimed. The features of various implementing embodimentsmay be combined to form further embodiments of the disclosed concepts.

What is claimed is:
 1. A putter comprising: a shaft; a grip provided onat least an upper end of the shaft; a head; and a connector including afirst part attached to the shaft and a second part connected to thehead, wherein the first part and the second part define a ball jointconnection between the shaft and the head that are configured to connectthe head to the shaft in a range of angular orientations to permit a lieangle and a loft angle of the head to be adjusted and fixed in aselected orientation relative to the shaft.
 2. The putter of claim 1wherein the first part of the connector further comprises: a ball endincluding a cylindrical stub shaft adapted to be attached to a lower endof the shaft and a spherical lower portion.
 3. The putter of claim 2wherein the second part of the connector further comprises: a receptaclethat defines a partially spherical surface; and a threaded lockingmember that may be loosened to change an angular orientation of the headrelative to the shaft and tightened to fix the angular orientation ofthe head relative to the shaft.
 4. The putter of claim 3 wherein thereceptacle further comprises: an adapter having a plurality of fingerson an upper end that have an outer surface that form a frustum of a conewith an increasing diameter in a vertical direction, and wherein thehead defines an opening that receives the adapter; and a lower portionthat defines a threaded opening that receives the threaded lockingmember; wherein the threaded locking member loosens an engagement of thefingers on the ball end by extending the adapter out of the opening, andwherein the threaded locking member tightens the engagement of thefingers by drawing the adapter into the opening.
 5. The putter of claim3 wherein the receptacle further comprises: a socket having a partiallyspherical surface on an upper end that is secured in an opening in thehead, and wherein the socket defines a threaded hole that opens into thepartially spherical surface; and a threaded fastener is received in thethreaded hole, wherein the fastener is untightened to loosen anengagement of the fastener on the ball end, and wherein the threadedfastener is tightened to fix the ball end in place in the socket.
 6. Theputter of claim 5 wherein the opening in the head includes a shoulderthat is disposed above the spherical lower portion of the ball end whenthe ball end is disposed in the opening in the head.
 7. The putter ofclaim 6 wherein the shoulder has a lower surface that is a concave ringthat conforms to a part of the spherical lower portion of the ball end.8. The putter of claim 7 wherein the socket has a threaded outer surfacein the opening in the head has a threaded inner surface, wherein thesocket is retained in the opening by the threaded outer surface engagingthe threaded inner surface, wherein a shoulder is provided on a lowerend of the socket and a countersink bore is defined in the lower surfaceof the head, and wherein the socket is screwed into the opening in thehead to engage the shoulder with the countersink bore.
 9. The putter ofclaim 1 wherein the shaft further comprises: a lower portion; an upperportion; and a connector assembly adapted to secure the upper portion ofthe shaft to the lower portion of the shaft, wherein the shaft isadapted to function as a belly putter.
 10. The putter of claim 9 furthercomprises: an intermediate grip provided on an upper end of the lowerportion.
 11. The putter of claim 1 wherein the shaft further comprises:a lower portion; an extended length upper portion; and a connectorassembly adapted to secure the extended length upper portion of theshaft to the lower portion of the shaft, wherein the shaft is adapted tofunction as a long putter.
 12. The putter of claim 11 further comprises:an intermediate grip provided on an upper end of the lower portion. 13.A putter comprising: a putter head; a shaft connected to the putterhead, wherein the shaft has a lower portion that includes a firstportion of a connector assembly and an upper portion that includes asecond portion of the shaft; and a first grip provided on the lowerportion of the shaft below and adjacent to the first portion of theconnector assembly, and a second grip provided on the upper portion ofthe shaft in a spaced relationship relative to the second portion of theconnector assembly and adjacent to an upper end of the upper portion ofthe shaft.
 14. The putter of claim 13 wherein the upper portion of theshaft has a length LB that is less than the length of the lower portionof the shaft.
 15. The putter of claim 13 wherein the upper portion ofthe shaft has a length LL that is greater than the length of the lowerportion of the shaft.
 16. The putter of claim 13 wherein the upperportion of the shaft may be selected from a first portion that has alength LB that is less than the length of the lower portion of theshaft, and a second upper portion of the shaft that has a length LL, andwherein the first portion is interchangeable with the second portion.17. The putter of claim 13 wherein the shaft is configured to connectthe head to the shaft in a range of angular orientations to permit a lieangle and a loft angle of the head to be adjusted and fixed in aselected orientation relative to the shaft.
 18. The putter of claim 13wherein the shaft is connected to the putter head by a ball joint thatfurther comprises: a ball end including a cylindrical stub shaft adaptedto be attached to a lower end of the shaft and a spherical lowerportion.
 19. The putter of claim 18 wherein the ball joint furthercomprises: a receptacle on the putter head that defines a partiallyspherical surface; and a threaded locking member that may be loosened tochange an angular orientation of the head relative to the shaft andtightened to fix the angular orientation of the head relative to theshaft.